This research will test the hypothesis that Growth Hormon mediates the effects of photoperiod on body composition in the golden hamster. The study will determine: 1) whether enhanced body weight gain in hamsters exposed to short days is associated with decreased GH secretion; 2) whether high-fat diets enhance short day induced body weight gain in hamsters by further suppressing GH secretion; and 3) whether treatment with GH-releasing hormone to enhance GH secretion will decrease short day and high fat induced weight gain.